Gas pollution abatement systems such as regenerative thermal oxidizers (RTOs) and recuperative thermal oxidizers (RCOs) are conventionally used for destroying volatile organic compounds (VOCs) in high flow, low concentration emissions from industrial and power plants. Such systems typically require high oxidation temperatures in order to achieve high VOC destruction. In RTO's for example, to achieve high heat recovery efficiency, the “dirty” process gas which is to be treated is preheated before oxidation. A heat exchanger column is typically provided to preheat these gases. The column is usually packed with a heat exchange material having good thermal and mechanical stability and sufficient thermal mass. In operation, the process gas is fed through a previously heated heat exchanger column, which, in turn, heats the process gas to a temperature approaching or attaining its VOC oxidation temperature. This pre-heated process gas is then directed into a combustion zone where any incomplete VOC oxidation is usually completed. The treated now “clean” gas is then directed out of the combustion zone and back through the heat exchanger column, or through a second heat exchange column. As the hot oxidized gas continues through this column, the gas transfers its heat to the heat exchange media in that column, cooling the gas and pre-heating the heat exchange media so that another batch of process gas may be preheated prior to the oxidation treatment. Usually, a regenerative thermal oxidizer has at least two heat exchanger columns which alternately receive process and treated gases. This process is continuously carried out, allowing a large volume of process gas to be efficiently treated.
Over time, contaminants such as particulate matter can accumulate in the media beds of abatement equipment. This increases the pressure drop across the media beds, and leads to a reduction in the efficiency of the unit, both in terms of the power required for airflow through the unit, and the heat exchange efficiency of the media.
The use of electrostatic precipitators and cyclone dust collectors upstream of the abatement equipment can help reduce particulate accumulation. In addition, to the extent the contaminants are burnable (e.g., organic contaminants), a “bake out” procedure can be used to help rid the media of burnable contaminants. Typical bake out procedures involve the controlled heating of regions of the media bed to temperatures sufficient for destroying the burnable contaminants.
Water washing is another technique used to remove contaminants from media beds. This typically involves manually spraying the media bed with a fire hose or the like. More specifically, the abatement equipment is shut down and allowed to cool, and an operator enters the equipment above the media bed via an access opening. The operator then uses a fire hose or the like connected to a fluid source under pressure to spray the media bed in an effort to remove embedded contaminants.
It would be desirable to provide apparatus for water washing media that results in more uniform washing, limits the amount of water that is splashed on the equipment insulation and walls, and reduces operator error, operator's physical exertion, and the likelihood of injury.